The present invention is a further development of the subject matter of my U.S. Pat. No. 3,795,160 and application Ser. No. 505,393 filed Sept. 12, 1974. The invention set forth in the foregoing patent and patent application utilize a separate guide sleeve which engages a guide element on the free end of the boring bar. The present invention omits the need for a costly sleeve and minimizes the length of the boring bar to thus reduce the cost of such tool.